| abstract |
57 Disclosed are catalysts for the polymerisation of olefins obtained by the reaction of an AI-alkyl compound and a silicon compound of the formulan where R i , R 2 , R 3 , and R 4 are hydrocarbyl radicals, with a solid catalyst component comprising a titanium halide or halogen alcoholate and an electron-donor compound having specific characteristics of extractability with AI-triethyl, supported on an active magnesium halide. |